Tubing anchor



sept. 15, 1970 J. R. BRo'wN 3,528,500

' TUBING Ammon Filed Feb. 24, 1969 A 5 sheets-sheet 1 o wAvr-g v @2 l .2V y. my

Afro/mers J. RL BROWN TUBING ANCHOR sept. 15, 1970 5 Sheets-Sheet 2 Filed Feb. 24. 1969 :JOE R ROWN INVEUR.

A Troma-y y .'5 Sheets-$heet J. R. BROWN TUBING ANCHOR SW@ B5, 1970 Filed Feb. 24, 1969 1 N l. E :-f F ,nf F. FEE n T 1 H nzw u n 11.22 n n ET JJ. f Mads* l v A Trae/wy United States Patent O 4 Claims ABSTRACT F THE DISCLOSURE An anchor assembly for Well tubing strings employing hydrostatic pressure-actuated anchor means and threaded connection means operable by right-hand rotation of the tubing string to release the anchor means.

In oil wells which employ reciprocating pumps operating inside of a string of tubing, it is necessary to anchor the tubing string against movement which usually results from the frictional forces produced by the pump plunger in its reciprocating movements inside the pump barrel which forms a part of the pipe string. This movement inside the surrounding casing, if uncontrolled, may damage both the tubing and casing, as well as the sucker rod string.

`Conventional tubing anchors employ various types of mechanical connectors or gripping devices which are of comparatively complicated construction, require special iittings to be pre-installed in the well casings for engagement by the anchors, are subject to various diliiculties in installation and release, and often are subject to slippage or accidental release due to the vibratory forces accompanying the pumping operation and to expansion and contraction of the tubing string by reason of temperature dilereuces between the pumped fluids and temperatures externally of the tubing string.

The present invention is directed to an improvement in such tubing anchors by employing a tubular mandrel insertible in the tubing string as a part thereof and carrying a relatively simple form of anchor assembly which is actuatable by the hydrostatic head of fluid in the tubing string to anchor the tubing string to the surrounding well wall, generally casing, and which employs a threaded connection between the mandrel and the anchor assembly operable by right-hand rotation of the tubing string to release the anchor means in order to permit withdrawal of the tubing string from the well.

A primary object of this invention is to provide a hydrostatic pressure-actuated tubing anchor which is of relatively simple mechanical construction and adapted for relatively easy installation and release.

An important object is the provision of such a hydrostatic pressure-actuated tubing anchor including a lefthand thread connection operable by right-hand rotation of the tubing to effect release of the anchor.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordanace with this invention.

In the drawing:

FIG. l is a longitudinal, quarter-sectional View of the anchor installed in a tubing string and inserted in a well casing, the anchor elements being shown in their nonactuated condition;

ICC

FIG. 2 is a view similar to FIG. 1, showing the anchor elements actuated in casing-gripping condition;

FIG. 3 is a View similar to FIG. 2, showing the anchor parts released preparatory to withdrawing the tubing string from the well;

FIG. 4 is a view showing the tubing string, anchor assembly and pumping string installed in a well;

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 1; and

FIG. 6 is a cross-sectional View taken on line 6 6 of FIG. 2.

Referring lirst to FIG. 4, there is shown an assemblage of apparatus for equipping a pump in a well which includes a device in accordance with this invention. As seen in FIG. 4, a well casing C extends through an oil producing formation F, with which the casing is in communication by means of perforations P through which production fluids L, particularly oil, water, or both,

enter casing C and rise therein to a level, indicated at E. The top of the casing is equipped with the usual casing head H through which extends a string of production tubing T having a side outlet O.

The lower end of tubing T has connected thereto an anchor device in accordance with this invention, designated by the letter A, and the lower end of the latter is connected to a pumping unit, designated particularly by the letter U, of any suitable and generally conventional design. For illustrative purposes, the pumping unit comprises a tubular barrel B, the lower end of which defines the perforate screen S which extends into the body of iiuid L. A conventional standing valve V is positioned in the bore of barrel B above screen S. A working valve or plunger W is mounted in barrel B above the standing valve for reciprocation by means of the sucker rods R which extend through the upper end of the tubing string for connection to the usual walking beam or other conventional power-operated reciprocating device (not shown).

Anchor device A comprises a tubular sub or mandrel 10 having an externally right-hand threaded pin 12 at its upper end adapted to be threadedly received by cornplementary right-hand threads in a collar 14 which connects the upper end of the mandrel to an adjacent section of tubing T. The lower end of mandrel 10 has a similar externally threaded pin 13 receivable in a collar 15 by which the lower end of the mandrel is connected to the upper end of barerl B or to an intervening section of tubing string T. Mandrel 10 has a bore 16 which is dirnensioned to be substantially liush with the bores of tubing T and barrel B so that the mandrel effectively forms a part of tubing T.

A cage sleeve 1S surrounds an upper portion of mandrel 10 and is releasably connected to the latter by means of a tubular bushing 20 having a section of external righthand threads 21 receivable in a corresponding section of internal threads 22 in the upper end of the bore of cage 18. Bushing 20 is provided with a section of left-hand threads 24, preferably of coarser form than threads 21 and 22. Threads 24 are adapted to be threadedly engaged by a complementary section of left-hand threads 25 provided about the exterior of the lower end portion of collar 14. Threads 24 and 25 constitute a means for releasing mandrel 10 from cage sleeve 18 in response to right-hand rotation of tubing T relative to sleeve cage 18. Inner and outer seal packings 26 and 27 are provided about bushing 20 to seal olf the latter about mandrel 10 and cage sleeve 18.

The lower portion of cage sleeve 18 is provided with a plurality of angularly spaced, generally rectangular radial windows or openings 28, in which are mounted wedgeshaped slips 29 for movement radially outwardly and inwardly of openings 28. The outer face of slips 29 are provided with wickers or teeth 30 adapted to grip the surrounding well wall, such as casing C, when urged outwardly. Mounted inside cage sleeve 18 between bushing 20 and slips 29 is a slip expander or actuator 31, the upper portion of which is generally cylindrical in external shape and terminating at its lower end in an inwardly tapering, generally conical nose 32, the taper of which is generally complementary to the upward and outward taper of inner face 33 of the slips. With this relation of the actuator and slips, it will be seen that relative downward movement of the actuator will urge slips 29 radially outwardly while relative upward movement of the actuator will release the slips for inward movement. Acutator 31 is initially held in retracted relation relative to slips 29 by means of one or more shear pins 34 which extend through cage sleeve 18 into the outer surface of actuator 31. A packing ring, such as an O-ring seal, is disposed about the exterior of the upper end of actuator 31 to slidably seal with the inner wall of cage sleeve 18. Another packing ring 36, such as an O-ring seal, is mounted in the bore of actuator 31 near its lower end to slidably seal with the exterior of mandrel 10. The upper end of actuator 31 forms a piston surface 37 which is acted upon by hydrostatic fluid pressure applied from the bore 16 of the mandrel through radial ports 38, as will be described subsequently. An abutment ring 39 is mounted in the exterior of mandrel at a point initially below slips 29 and projects slightly into the bore of cage sleeve 18, so as to pass the inner faces of slips 29 and engage the lower end of actuator 31, for releasing the slips as will be described subsequently.

Any number of the slips 29 may be employed, but generally three, located 120 apart, will be found preferable and lwill serve to effectively balance the forces involved in anchoring the tubing to the casing.

In operation, the string of tubing T carrying the pumping unit U and anchoring device A will be run into the well to the desired level at which the suction portion of the pumping unit is submerged in the Ibody of production uid L accumulated in casing C. The parts of anchor device A will be generally in the positions shown in FIG. l, namely, threaded sections 24 and 25 engaged to secure the cage sleeve to mandrel 10 and placing ports i 38 into communication with the interior of cage 18, generally opposite piston surface 37 and between seals 26 and 36. Actuator 31 will be in its retracted position, being held by shear screws 34, and slips 29 will thereby be in their released or retracted relation with respect to cage 18.

When the tubing string has been lowered to the desired depth in the well, the tubing will be filled with a column of liquid to a height suicient to exert through ports 38 at least the amount of hydrostatic pressure required to urge slips 29 into strong anchoring engagement with casing C. The liquid column in the tubing sufcient to actuate slips 29 by the force exerted through actuator 31 may be applied initially by filling the tubing through outlet fitting O to the required height. However, if desired, the pump may be operated for a short period sufficient to raise a column of liquid from the liquid in the well to a height at which the hydrostatic head will exert effective setting forces on the slips. The hydrostatic head will, of course, be exerted through ports 38 against the upper end of actuator 31 and the shear screws 34 will be selected of such strengths as to restrain movement of actuator 31 until sufficient hydrostatic head has been developed to break the shear screws and drive the actuator downwardly relatively to slips 29, thereby urging the latter radially outwardly into gripping engagement with the wall of casing C. When the slips have thus been actuated, as best seen in FIGS. 2 and 4, pumping of the well fluids may be conducted while the tubing string remains firmly anchored to the surrounding casing. The hydrostatic head being maintained on the actuator and the balanced arrangement of the slips will serve to maintain this strong gripping engagement under the vivratory conditions produced by the reciprocation of the rod string and this gripping force will be unaffected by expansion and contraction of the tubing string by reason of the temperature changes.

When it is desired to release the anchor, this may be accomplished very simply by rotating the tubing string to the right, which will normally tend to tighten all of the connections between the tubing sections, but which, by reason of the left-hand threads 24 and 25 will cause collar 14 to unscrew from bushing 20. Once this threaded connection has been broken, as best seen in FIG. 3, the tubing string may be raised. While the rotation occurs to effect this release, the slips -will remain in gripping engagement with the wall of casing C, since actuator 31 will not be affected initially by this rotation and will remain in expansive engagement with the slips. However,.

once the connection with bushing 20 has been broken and tubing string T pulled upwardly, abutment ring 39 will be brought into engagement with the lower end of actuator 31 and as upward force continues to be applied to the tubing string, the engagement of ring 39 with actuator 31 will raise the latter upwardly out of its expansive engagement with slips 29. The latter will then be free to retract and will be forced to do so as continued upward force is applied to tubing T sufficient to increase the pressure of ring 39 against the lower end of actuator 31. The entire tubing string may then be pulled out of the well. It will be evident, of course, that as ports 38 are elevated above seal ring 26, the column of uid in the tubing string will drain through ports 38 into casing C, thus relieving the string of its fluid load as it is withdrawn from the well.

From the foregoing it will be evident that the anchor structure herein described is of the simplest mechanical form and employs an exceptional simple type of release mechanism to release the anchor structure in order to enable the tubing string and its appurtenances to be withdrawn from the well.

It will lbe understood that various modifications and changes may be made in the details of the illustrative embodiment within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. An anchor device for well tubing strings, comprislng:

(a) a tubular mandrel connectible into a tubing string to form a part thereof;

(b) a cage sleeve mounted about the upper portion of the mandrel;

(c) an annular bushing secured to the upper end of said sleeve and surrounding said mandrel;

(d) complementary left-hand thread sections in the Ibore of the bushing and on said mandrel for connecting said sleeve to the mandrel and operable in response to right-hand rotation of the mandrel relative to the sleeve to release the mandrel from said sleeve;

(e) a plurality of angularly spaced radial openings in the lower portion of said sleeve;

(f) pipe-gripping slips mounted in said openings for radial movement relative to the sleeve;

(g) an annular slip actuator slidably disposed about said mandrel inside said cage sleeve between said bushing and said slips for axial movement between a downwardly advanced position expansibly urging said slips outwardly of the sleeve and an upper retracted position releasing said slips for radially retractive movement inwardly of said sleeve;

(h) port means in said mandrel providing hydrostatic pressure communication between the mandrel bore and the interior of said sleeve above said actuator; and

(i) frangible means initially securing said actuator in its retracted position and releasafble in response to hydrostatic pressure exerted on said actuator.

2. An anchor device according to claim 1 including abutment means on the mandrel below said actuator abuttable with the lower end of the actuator in response to upward movement of the mandrel to move the actuator to said retracted position relative to said slips.

3. An anchor device according to claim 1 including:

(a) collar means for connecting the upper end of said mandrel to the tubing string; and

(b) said left-hand thread section on the mandrel being formed about the exterior of said collar means.

4. An anchor device according to claim 1, wherein said bushing has an external section of right-hand threads for securing said bushing to said cage sleeve.

l5 DAVID H.

References Cited UNITED STATES PATENTS 12/1957 Long 166-212 X 2/1959 Baker et al. 166-212 12/1961 Conrad 166-212 10/1965 Brown 166--216 10/1968 Page 166-212 6/1969 Brown 166-212 BROWN, Primary Examiner U.S. Cl. X.R. 

